<!doctype html>
<html>
<head>
    <meta charset="utf-8">
    <title>3D烟花</title>
    <style>
        html,
        body {
            margin: 0px;
            width: 100%;
            height: 100%;
            overflow: hidden;
            background: #000;
        }

        #canvas {
            width: 100%;
            height: 100%;
        }
    </style>
</head>
<body>
    <canvas id="canvas"></canvas>
    <script>
        function initVars() {
            pi = Math.PI;
            ctx = canvas.getContext("2d");
            canvas.width = canvas.clientWidth;
            canvas.height = canvas.clientHeight;
            cx = canvas.width / 2;
            cy = canvas.height / 2;
            playerZ = -25;
            playerX = playerY = playerVX = playerVY = playerVZ = pitch = yaw = pitchV = yawV = 0;
            scale = 600;
            seedTimer = 0; seedInterval = 5, seedLife = 100; gravity = .02;
            seeds = new Array();
            sparkPics = new Array();
            s = "https://cantelope.org/NYE/";
            for (i = 1; i <= 10; ++i) {
                sparkPic = new Image();
                sparkPic.src = s + "spark" + i + ".png";
                sparkPics.push(sparkPic);
            }
            sparks = new Array();
            pow1 = new Audio(s + "pow1.ogg");
            pow2 = new Audio(s + "pow2.ogg");
            pow3 = new Audio(s + "pow3.ogg");
            pow4 = new Audio(s + "pow4.ogg");
            frames = 0;
        }
        function rasterizePoint(x, y, z) {
            var p, d;
            x -= playerX;
            y -= playerY;
            z -= playerZ;
            p = Math.atan2(x, z);
            d = Math.sqrt(x * x + z * z);
            x = Math.sin(p - yaw) * d;
            z = Math.cos(p - yaw) * d;
            p = Math.atan2(y, z);
            d = Math.sqrt(y * y + z * z);
            y = Math.sin(p - pitch) * d;
            z = Math.cos(p - pitch) * d;
            var rx1 = -1000, ry1 = 1, rx2 = 1000, ry2 = 1, rx3 = 0, ry3 = 0, rx4 = x, ry4 = z, uc = (ry4 - ry3) * (rx2 - rx1) - (rx4 - rx3) * (ry2 - ry1);
            if (!uc) return { x: 0, y: 0, d: -1 };
            var ua = ((rx4 - rx3) * (ry1 - ry3) - (ry4 - ry3) * (rx1 - rx3)) / uc;
            var ub = ((rx2 - rx1) * (ry1 - ry3) - (ry2 - ry1) * (rx1 - rx3)) / uc;
            if (!z) z = .000000001;
            if (ua > 0 && ua < 1 && ub > 0 && ub < 1) {
                return {
                    x: cx + (rx1 + ua * (rx2 - rx1)) * scale,
                    y: cy + y / z * scale,
                    d: Math.sqrt(x * x + y * y + z * z)
                };
            } else {
                return {
                    x: cx + (rx1 + ua * (rx2 - rx1)) * scale,
                    y: cy + y / z * scale,
                    d: -1
                };
            }
        }
        function spawnSeed() {
            seed = new Object();
            seed.x = -50 + Math.random() * 100;
            seed.y = 25;
            seed.z = -50 + Math.random() * 100;
            seed.vx = .1 - Math.random() * .2;
            seed.vy = -1.5;//*(1+Math.random()/2);
            seed.vz = .1 - Math.random() * .2;
            seed.born = frames;
            seeds.push(seed);
        }
        function splode(x, y, z) {
            t = 5 + parseInt(Math.random() * 150);
            sparkV = 1 + Math.random() * 2.5;
            type = parseInt(Math.random() * 3);
            switch (type) {
                case 0:
                    pic1 = parseInt(Math.random() * 10);
                    break;
                case 1:
                    pic1 = parseInt(Math.random() * 10);
                    do { pic2 = parseInt(Math.random() * 10); } while (pic2 == pic1);
                    break;
                case 2:
                    pic1 = parseInt(Math.random() * 10);
                    do { pic2 = parseInt(Math.random() * 10); } while (pic2 == pic1);
                    do { pic3 = parseInt(Math.random() * 10); } while (pic3 == pic1 || pic3 == pic2);
                    break;
            }
            for (m = 1; m < t; ++m) {
                spark = new Object();
                spark.x = x; spark.y = y; spark.z = z;
                p1 = pi * 2 * Math.random();
                p2 = pi * Math.random();
                v = sparkV * (1 + Math.random() / 6)
                spark.vx = Math.sin(p1) * Math.sin(p2) * v;
                spark.vz = Math.cos(p1) * Math.sin(p2) * v;
                spark.vy = Math.cos(p2) * v;
                switch (type) {
                    case 0: spark.img = sparkPics[pic1]; break;
                    case 1:
                        spark.img = sparkPics[parseInt(Math.random() * 2) ? pic1 : pic2];
                        break;
                    case 2:
                        switch (parseInt(Math.random() * 3)) {
                            case 0: spark.img = sparkPics[pic1]; break;
                            case 1: spark.img = sparkPics[pic2]; break;
                            case 2: spark.img = sparkPics[pic3]; break;
                        }
                        break;
                }
                spark.radius = 25 + Math.random() * 50;
                spark.alpha = 1;
                spark.trail = new Array();
                sparks.push(spark);
            }
            switch (parseInt(Math.random() * 4)) {
                case 0: pow = new Audio(s + "pow1.ogg"); break;
                case 1: pow = new Audio(s + "pow2.ogg"); break;
                case 2: pow = new Audio(s + "pow3.ogg"); break;
                case 3: pow = new Audio(s + "pow4.ogg"); break;
            }
            d = Math.sqrt((x - playerX) * (x - playerX) + (y - playerY) * (y - playerY) + (z - playerZ) * (z - playerZ));
            pow.volume = 1.5 / (1 + d / 10);
            pow.play();
        }
        function doLogic() {
            if (seedTimer < frames) {
                seedTimer = frames + seedInterval * Math.random() * 10;
                spawnSeed();
            }
            for (i = 0; i < seeds.length; ++i) {
                seeds[i].vy += gravity;
                seeds[i].x += seeds[i].vx;
                seeds[i].y += seeds[i].vy;
                seeds[i].z += seeds[i].vz;
                if (frames - seeds[i].born > seedLife) {
                    splode(seeds[i].x, seeds[i].y, seeds[i].z);
                    seeds.splice(i, 1);
                }
            }
            for (i = 0; i < sparks.length; ++i) {
                if (sparks[i].alpha > 0 && sparks[i].radius > 5) {
                    sparks[i].alpha -= .01;
                    sparks[i].radius /= 1.02;
                    sparks[i].vy += gravity;
                    point = new Object();
                    point.x = sparks[i].x;
                    point.y = sparks[i].y;
                    point.z = sparks[i].z;
                    if (sparks[i].trail.length) {
                        x = sparks[i].trail[sparks[i].trail.length - 1].x;
                        y = sparks[i].trail[sparks[i].trail.length - 1].y;
                        z = sparks[i].trail[sparks[i].trail.length - 1].z;
                        d = ((point.x - x) * (point.x - x) + (point.y - y) * (point.y - y) + (point.z - z) * (point.z - z));
                        if (d > 9) {
                            sparks[i].trail.push(point);
                        }
                    } else {
                        sparks[i].trail.push(point);
                    }
                    if (sparks[i].trail.length > 5) sparks[i].trail.splice(0, 1);
                    sparks[i].x += sparks[i].vx;
                    sparks[i].y += sparks[i].vy;
                    sparks[i].z += sparks[i].vz;
                    sparks[i].vx /= 1.075;
                    sparks[i].vy /= 1.075;
                    sparks[i].vz /= 1.075;
                } else {
                    sparks.splice(i, 1);
                }
            }
            p = Math.atan2(playerX, playerZ);
            d = Math.sqrt(playerX * playerX + playerZ * playerZ);
            d += Math.sin(frames / 80) / 1.25;
            t = Math.sin(frames / 200) / 40;
            playerX = Math.sin(p + t) * d;
            playerZ = Math.cos(p + t) * d;
            yaw = pi + p + t;
        }
        function rgb(col) {
            var r = parseInt((.5 + Math.sin(col) * .5) * 16);
            var g = parseInt((.5 + Math.cos(col) * .5) * 16);
            var b = parseInt((.5 - Math.sin(col) * .5) * 16);
            return "#" + r.toString(16) + g.toString(16) + b.toString(16);
        }
        function draw() {
            ctx.clearRect(0, 0, cx * 2, cy * 2);
            ctx.fillStyle = "#ff8";
            for (i = -100; i < 100; i += 3) {
                for (j = -100; j < 100; j += 4) {
                    x = i; z = j; y = 25;
                    point = rasterizePoint(x, y, z);
                    if (point.d != -1) {
                        size = 250 / (1 + point.d);
                        d = Math.sqrt(x * x + z * z);
                        a = 0.75 - Math.pow(d / 100, 6) * 0.75;
                        if (a > 0) {
                            ctx.globalAlpha = a;
                            ctx.fillRect(point.x - size / 2, point.y - size / 2, size, size);
                        }
                    }
                }
            }
            ctx.globalAlpha = 1;
            for (i = 0; i < seeds.length; ++i) {
                point = rasterizePoint(seeds[i].x, seeds[i].y, seeds[i].z);
                if (point.d != -1) {
                    size = 200 / (1 + point.d);
                    ctx.fillRect(point.x - size / 2, point.y - size / 2, size, size);
                }
            }
            point1 = new Object();
            for (i = 0; i < sparks.length; ++i) {
                point = rasterizePoint(sparks[i].x, sparks[i].y, sparks[i].z);
                if (point.d != -1) {
                    size = sparks[i].radius * 200 / (1 + point.d);
                    if (sparks[i].alpha < 0) sparks[i].alpha = 0;
                    if (sparks[i].trail.length) {
                        point1.x = point.x;
                        point1.y = point.y;
                        switch (sparks[i].img) {
                            case sparkPics[0]: ctx.strokeStyle = "#f84"; break;
                            case sparkPics[1]: ctx.strokeStyle = "#84f"; break;
                            case sparkPics[2]: ctx.strokeStyle = "#8ff"; break;
                            case sparkPics[3]: ctx.strokeStyle = "#fff"; break;
                            case sparkPics[4]: ctx.strokeStyle = "#4f8"; break;
                            case sparkPics[5]: ctx.strokeStyle = "#f44"; break;
                            case sparkPics[6]: ctx.strokeStyle = "#f84"; break;
                            case sparkPics[7]: ctx.strokeStyle = "#84f"; break;
                            case sparkPics[8]: ctx.strokeStyle = "#fff"; break;
                            case sparkPics[9]: ctx.strokeStyle = "#44f"; break;
                        }
                        for (j = sparks[i].trail.length - 1; j >= 0; --j) {
                            point2 = rasterizePoint(sparks[i].trail[j].x, sparks[i].trail[j].y, sparks[i].trail[j].z);
                            if (point2.d != -1) {
                                ctx.globalAlpha = j / sparks[i].trail.length * sparks[i].alpha / 2;
                                ctx.beginPath();
                                ctx.moveTo(point1.x, point1.y);
                                ctx.lineWidth = 1 + sparks[i].radius * 10 / (sparks[i].trail.length - j) / (1 + point2.d);
                                ctx.lineTo(point2.x, point2.y);
                                ctx.stroke();
                                point1.x = point2.x;
                                point1.y = point2.y;
                            }
                        }
                    }
                    ctx.globalAlpha = sparks[i].alpha;
                    ctx.drawImage(sparks[i].img, point.x - size / 2, point.y - size / 2, size, size);
                }
            }
        }
        function frame() {
            if (frames > 100000) {
                seedTimer = 0;
                frames = 0;
            }
            frames++;
            draw();
            doLogic();
            requestAnimationFrame(frame);
        }
        window.addEventListener("resize", () => {
            canvas.width = canvas.clientWidth;
            canvas.height = canvas.clientHeight;
            cx = canvas.width / 2;
            cy = canvas.height / 2;
        });
        initVars();
        frame();</script>
    <div style="text-align:center;">
    </div>
</body>
</html>